Alkali metal salts of 2-[{4-(3-methoxypropoxy)-3-methylpyridin-2-yl}methylsulfinyl]-1H-benzimidazole are known to be useful as anti-ulcer agents and the like because they have the effect of inhibiting gastric acid secretion (see for example U.S. Pat. No. 5,045,552).
Although salts of the proton pump inhibitor omeprazole with amines are known (see for example International Patent Publications (pamphlets) WO 03/74514 and WO 94/27988 and European Patent Publication 124495), salts of 2-[{4-(3-methoxypropoxy)-3-methylpyridin-2-yl}methylsulfinyl]-1H-benzimidazole with amines are not known.
The crystallization process of salts of compounds such as omeprazole that act as proton pump inhibitors with amines is also not known to be useful for removing impurities and the like.
Moreover, no method is known of obtaining alkali metal salts of 2-[{4-(3-methoxypropoxy)-3-methylpyridin-2-yl}methylsulfinyl]-1H-benzimidazole from salts of 2-[{4-(3-methoxypropoxy)-3-methylpyridin-2-yl}methylsulfinyl]-1H-benzimidazole with amines.
On the other hand, methods are known of manufacturing a 2-[{4-(3-methoxypropoxy)-3-methylpyridin-2-yl}methylsulfinyl]-1H-benzimidazole sodium salt in which the content of the impurity (2-[{4-(3-methoxypropoxy)-3-methylpyridin-2-yl}methylsulfonyl]-1H-benzimidazole (hereinafter simply referred to as “sulfone”) is reduced to between 0.82% and 0.30% (see for example European Patent Publication 1000943).